Long term objective of this research is the quantitative description of the placental exchange of metabolites between mother and fetus. Sheep with chronic catheters in the maternal and fetal circulations will be studied in order to determine the rates of uterine and umbilical uptakes of glucose and lactate at different concentrations of maternal and fetal plasma glucose. The effect of insulin administration to the fetus on umbilical glucose uptake and placental glucose clearance will be studied also. BIBLIOGRAPHIC REFERENCES: Morriss, Jr., F.H., E.L. Makowski, G. Meschia & F.C. Battaglia (1975). The glucose/oxygen quotient of the term human fetus. Biol. Neonate 25: 44-52; Resnik, R., F.C. Battaglia, E.L. Makowski, G. Meschia (1975). The effect of actinomycin D on estrogen-induced uterine blood flow. Am. J. Ob. Gyn. 122: 273-277.